1. Field of the Invention
The present invention relates to an electronic musical instrument which provides a user with musical performance guide by indicating a musical performance operating element that the user is expected to play by use of musical performance data.
2. Description of the Related Art
Although a beginner desires to play a song on the electronic musical instrument, he or she is not sure which note should be played and when and how long the note should be played. Conventionally, there are electronic musical instruments having a musical performance guide capability for reproducing musical performance data of the user's desired song and indicating the note the user should play on a display or by a guide lamp. The conventional electronic musical instruments having such a musical performance guide capability are described in the following documents 1 to 3:    Document 1: Japanese Patent Publication No. 2707853    Document 2: Japanese Unexamined Patent Publication No. 2004-101979    Document 3: Yamaha Corporation, PORTATONE EZJ-210 Manual, p. 32, http://www2.yamaha.co.jp/manual/pdf/emi/japan/port/ezj210_ja_om_a0.pdf (searched on Dec. 8, 2010).
By the musical performance guide capability of the conventional electronic musical instrument, when a song which a user desires to practice is reproduced to reach the timing at which the user is supposed to play, the electronic musical instrument indicates a key corresponding to a note which the user is supposed to play, so that the user learns on his own which note should be played and when the note should be played. Conventionally, furthermore, there is a musical performance guide capability by which, if an indicated key has not been played by the user at certain timing, the electronic musical instrument enters a waiting state to wait until the indicated key is played by the user. In this waiting state, the electronic musical instrument suspends the reading of musical performance data which is done in accordance with the progression of the song, and waits until the user plays the indicated key. When the user plays the indicated key, the electronic musical instrument generates a musical tone corresponding to the played key, and starts reading the following musical performance data to resume the reproduction of the song.
The operation of the conventional musical performance guide will be explained with an example of a keyboard musical instrument, referring to FIG. 8.
On the top row of FIG. 8, notes indicative of automatic musical performance data of a song which the user is to play are arranged in time sequence. On a row situated below the top row, note lengths of the respective notes indicated on the top row are indicated as long rectangles. On a row situated below the second row, key-depression periods each ranging from user's depression of a key corresponding to an above-described note to user's release of the key are indicated as long rectangles. In FIG. 8, however, note numbers of the respective notes are not shown. In FIG. 8, times t1, t2, t3, t4, t5 . . . are the times at which respective beats start. More specifically, each interval between the times is equivalent to a beat. The timing at which the first quarter note n1 indicative of the automatic musical performance data is expected to be generated is time t1. The timing at which the second quarter note n2 is expected to be generated is time t2. The timing at which the third half-note n3 is expected to be generated is time t3.
When the musical performance guide capability which the user can switch between on and off is turned on by the user for playing a song, automatic musical performance data is read out in sequence. At time t01 which is earlier by a certain period of time T than the time t1 at which the quarter note n1 is expected to generate, a guide lamp indicating a key having the tone pitch of the quarter note n1 is illuminated. Assume that even though the guide lamp had been illuminated at the time t01, the user has not depressed the key indicated by the guide lamp by the tone generation timing t1. As a result, the electronic musical instrument enters the waiting state to suspend the reading of the musical performance data to wait until the user depresses the indicated key. Assume that the user depresses the key indicated by the guide lamp at time t1′ which is later than the time t1. By the depression of the key, the guide lamp is distinguished, while the generation of a musical tone having the tone pitch of the depressed key starts at the time t1′ to keep generating the tone until the release of the key. In addition, the electronic musical instrument cancels the waiting state to read out the next musical performance data to prepare for the guide for the next quarter note n2. A period ranging from the time t01 to the time t1 is the certain period T, which is a short period equivalent to the note length of a thirty-second note, for example. In a case where the user has depressed a key different from the key indicated by the guide lamp, the electronic musical instrument judges the key-depression to be a failed depression, so that the electronic musical instrument considers that the correct key-depression has not been made by the time t1 to enter the waiting state to wait until the correct depression of the indicated key.
As described above, in the case where the key which is indicated by the guide lamp and corresponds to the tone pitch of the quarter note n1 is depressed by the user, the next automatic musical performance data is read out, with time t20 which is later by one beat than the time t1′ at which the key corresponding to the quarter note n1 has been depressed being defined as the timing at which the quarter note n2 is expected to generate. At a point in time which is earlier by the certain period T than the time t20, therefore, the guide lamp indicating a key corresponding to the tone pitch of the quarter note n2 is illuminated to offer the musical performance guide for the quarter note n2. As for the musical performance data for the quarter note n2 and the half note n3 as well, at respective points in time which are earlier by the certain period T than the respective times at which musical tones of the respective notes are expected to generate, the guide lamps indicating respective keys corresponding to the tone pitches of the notes n2, n3 are illuminated to offer the musical performance guide for the respective notes. In the case of FIG. 8, in spite of such a guide being offered for the user, the user has not depressed the keys indicated by the guide lamps by the respective tone-generation timings of the notes n2, n3. As a result, the electronic musical instrument enters the waiting state at the respective tone-generation timings of the notes n2, n3. The user then depresses the key corresponding to the quarter note n2 at time t2′ which is later than the tone-generation timing t20, so that the waiting state is canceled. Furthermore, the user depresses the key corresponding to the half note n3 at time t3′ which is later than the tone-generation timing t30, so that the waiting state is canceled. By the correct key-depression which leads to the cancel of the waiting state, the generation of a musical tone having the tone pitch of the guided note, that is, having the tone pitch of the depressed key starts to keep the generated musical tone until the release of the key, while the next musical performance data is read out to prepare for the guide for the next note.
By the above-described guide capability, immediately before the timing at which the user is expected to depress a key during the reproduction of a song which the user desires to practice, the electronic musical instrument provides the user with the guide which indicates the key that the user is expected to depress. If the user has not depressed the guided key by the originally set tone-generation timing, the electronic musical instrument enters the waiting state. If the user then depresses the guided key, the electronic musical instrument resumes the reproduction of the song. A corresponding musical tone will be generated for a period ranging from the depression of the key to the release of the key. This guide capability indicates only the note which should be depressed and the timing at which the key should be depressed, but does not indicate the timing at which the key should be released. Therefore, the conventional guide capability is disadvantageous in that if the user releases the key excessively early, the period during which the corresponding tone is generated is too short, ending up with interrupted musical performance.
In order to resolve this disadvantage, there is a conventional musical performance guide capability which enables the user to learn the timing at which keys should be released as well. By this conventional musical performance guide capability, regardless of the timing at which the user releases a key, the generation of a musical tone corresponding to the key is maintained until the note length of a note recorded in song data has passed, while the generation of the musical tone automatically stops when the note length of the note has passed. By the conventional musical performance guide, therefore, even if the user fails to release the key at the correct timing, the song played by the user sounds well. By repeatedly practicing the song by use of this musical performance guide capability, furthermore, the user can learn when to release keys.
The operation of this conventional musical performance guide will be explained with reference to FIG. 9. In FIG. 9 as well, an example of a keyboard musical instrument will be described.
On the top row of FIG. 9, notes indicative of automatic musical performance data of a song which the user is to play are arranged in time sequence. On a row situated below the top row, note lengths of the respective notes indicated on the top row are indicated as long rectangles. On a row situated below the second row, periods each ranging from user's depression of a key corresponding to an above-described note to user's release of the key are indicated as long rectangles. In FIG. 9, times t1, t2, t3, t4, . . . are the times at which respective beats start. More specifically, each interval between the times is equivalent to a beat. The timing at which the first quarter note n10 indicative of the automatic musical performance data is expected to be generated is time t1. The timing at which the second quarter note n11 is expected to be generated is time t2. The timing at which the third quarter note n12 is expected to be generated is time t3. The timing at which the fourth quarter note n13 is expected to be generated is time t4. The note length of the quarter note n10 is ta1. The note length of the quarter note n11 is ta2. The note length of the quarter note n12 is ta3. The note length of the quarter note n13 is ta4. Because each of the notes n10 to n13 is a quarter note, the respective note lengths ta1 to ta4 have the same length.
In a case where the user starts musical performance with the musical performance guide being switched to on, automatic musical performance data is read out in sequence, while at a point in time which is not shown but is earlier by a certain period of time than the time t1 at which the quarter note n10 is expected to be generated, a guide lamp indicative of a key corresponding to the tone pitch of the quarter note n10 is illuminated. Assume that the user recognizes the illuminated guide lamp and depresses the key indicated by the guide lamp at the time t1 to keep depressing the key for a period tb1. In this case, although the period tb1 is shorter than the note length ta1 of the quarter note n10, the length of an actually generated musical tone is prolonged to have the note length ta1. In the case where the key corresponding to the tone pitch of the quarter note n10 indicated by the guide lamp has been depressed, the next automatic musical performance data is read out to illuminate a guide lamp indicating a key corresponding to the tone pitch of the quarter note n11 at a point in time which is earlier by the certain period than the timing t2 at which the quarter note n11 is expected to be generated. Assume that the user similarly depresses the key indicated by the guide lamp at the time t2 to keep depressing the key for a period tb2. In this case, although the period tb2 is shorter than the note length ta2 of the quarter note n11, the length of an actually generated musical tone is prolonged to have the note length ta2. In the case where the key indicated by the guide lamp and corresponding to the tone pitch of the quarter note n11 is played, furthermore, the next automatic performance data is read out, while a guide lamp indicating a key corresponding to the tone pitch of the quarter note n12 is illuminated at a point in time which is earlier by the certain period of time than the time t3 at which the quarter note n12 is expected to be generated. Assume that the user similarly depresses the key indicated by the guide lamp at the time t3 to keep depressing the key for a period tb3. In this case, although the period tb3 is longer than the note length ta3 of the quarter note n12, the length of an actually generated musical tone is shrunk to have the note length ta3.
By this conventional musical performance guide capability, therefore, the respective musical tones are kept being generated for the respective note lengths recorded in the song data regardless of the respective timing at which the user has actually released the respective keys.